This proposal will assess and quantitate circulating stem cells in relation to chemotherapy. Recent observations have demonstrated that circulating stem cells increase markedly following chemotherapy in patients with cancer. The increased blood content of committed granulocyte precursors (as great as twentyfold to thirtyfold) facilitates the collection of quantities efficient for autologous stem cell reconstitution studies. The dose-response curve for most chemotherapeutic agents is steep, but dosage escalation is limited because of myelosuppression. Reconstitution of viable stem cell elements may provide the protective milieu for more intensive chemotherapy and thus, the potential for greater tumor cytoreduction. This grant will study the dynamics of circulating stem cells during chemotherapy and establish optimum procurement and preservation methodology. An animal model will be developed for stem cell reconstitution prior to initiation of clinical reconstitution attempts. The long-range goal is to determine the value of autologous stem cell support in enhancing the therapeutic effectiveness of chemotherapy. BIBLIOGRAPHIC REFERENCES: Richman, C.M., Weiner, R.S. and Yankee, R.A.: Increase in circulating stem cells following chemotherapy in man. Blood 47:1031-1039, 1976.